mtd: atmel-quadspi: add driver for Atmel QSPI controller

This driver add support to the new Atmel QSPI controller embedded into
sama5d2x SoCs. It expects a NOR memory to be connected to the QSPI
controller.

Signed-off-by: Cyrille Pitchen <[e-mail]>
Acked-by: Nicolas Ferre <[e-mail]>
Signed-off-by: Brian Norris <[e-mail]>

drivers/mtd/spi-nor/Kconfig

···
 	  Please note that some tools/drivers/filesystems may not work with
 	  4096 B erase size (e.g. UBIFS requires 15 KiB as a minimum).
 
+config SPI_ATMEL_QUADSPI
+	tristate "Atmel Quad SPI Controller"
+	depends on ARCH_AT91 || (ARM && COMPILE_TEST)
+	depends on OF && HAS_IOMEM
+	help
+	  This enables support for the Quad SPI controller in master mode.
+	  This driver does not support generic SPI. The implementation only
+	  supports SPI NOR.
+
 config SPI_FSL_QUADSPI
 	tristate "Freescale Quad SPI controller"
 	depends on ARCH_MXC || SOC_LS1021A || ARCH_LAYERSCAPE || COMPILE_TEST

drivers/mtd/spi-nor/Makefile

···
 obj-$(CONFIG_MTD_SPI_NOR)	+= spi-nor.o
+obj-$(CONFIG_SPI_ATMEL_QUADSPI)	+= atmel-quadspi.o
 obj-$(CONFIG_SPI_FSL_QUADSPI)	+= fsl-quadspi.o
 obj-$(CONFIG_SPI_HISI_SFC)	+= hisi-sfc.o
 obj-$(CONFIG_MTD_MT81xx_NOR)    += mtk-quadspi.o

drivers/mtd/spi-nor/atmel-quadspi.c

···
+/*
+ * Driver for Atmel QSPI Controller
+ *
+ * Copyright (C) 2015 Atmel Corporation
+ *
+ * Author: Cyrille Pitchen <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * This driver is based on drivers/mtd/spi-nor/fsl-quadspi.c from Freescale.
+ */
+
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/spi-nor.h>
+#include <linux/platform_data/atmel.h>
+#include <linux/of.h>
+
+#include <linux/io.h>
+#include <linux/gpio.h>
+#include <linux/pinctrl/consumer.h>
+
+/* QSPI register offsets */
+#define QSPI_CR      0x0000  /* Control Register */
+#define QSPI_MR      0x0004  /* Mode Register */
+#define QSPI_RD      0x0008  /* Receive Data Register */
+#define QSPI_TD      0x000c  /* Transmit Data Register */
+#define QSPI_SR      0x0010  /* Status Register */
+#define QSPI_IER     0x0014  /* Interrupt Enable Register */
+#define QSPI_IDR     0x0018  /* Interrupt Disable Register */
+#define QSPI_IMR     0x001c  /* Interrupt Mask Register */
+#define QSPI_SCR     0x0020  /* Serial Clock Register */
+
+#define QSPI_IAR     0x0030  /* Instruction Address Register */
+#define QSPI_ICR     0x0034  /* Instruction Code Register */
+#define QSPI_IFR     0x0038  /* Instruction Frame Register */
+
+#define QSPI_SMR     0x0040  /* Scrambling Mode Register */
+#define QSPI_SKR     0x0044  /* Scrambling Key Register */
+
+#define QSPI_WPMR    0x00E4  /* Write Protection Mode Register */
+#define QSPI_WPSR    0x00E8  /* Write Protection Status Register */
+
+#define QSPI_VERSION 0x00FC  /* Version Register */
+
+
+/* Bitfields in QSPI_CR (Control Register) */
+#define QSPI_CR_QSPIEN                  BIT(0)
+#define QSPI_CR_QSPIDIS                 BIT(1)
+#define QSPI_CR_SWRST                   BIT(7)
+#define QSPI_CR_LASTXFER                BIT(24)
+
+/* Bitfields in QSPI_MR (Mode Register) */
+#define QSPI_MR_SSM                     BIT(0)
+#define QSPI_MR_LLB                     BIT(1)
+#define QSPI_MR_WDRBT                   BIT(2)
+#define QSPI_MR_SMRM                    BIT(3)
+#define QSPI_MR_CSMODE_MASK             GENMASK(5, 4)
+#define QSPI_MR_CSMODE_NOT_RELOADED     (0 << 4)
+#define QSPI_MR_CSMODE_LASTXFER         (1 << 4)
+#define QSPI_MR_CSMODE_SYSTEMATICALLY   (2 << 4)
+#define QSPI_MR_NBBITS_MASK             GENMASK(11, 8)
+#define QSPI_MR_NBBITS(n)               ((((n) - 8) << 8) & QSPI_MR_NBBITS_MASK)
+#define QSPI_MR_DLYBCT_MASK             GENMASK(23, 16)
+#define QSPI_MR_DLYBCT(n)               (((n) << 16) & QSPI_MR_DLYBCT_MASK)
+#define QSPI_MR_DLYCS_MASK              GENMASK(31, 24)
+#define QSPI_MR_DLYCS(n)                (((n) << 24) & QSPI_MR_DLYCS_MASK)
+
+/* Bitfields in QSPI_SR/QSPI_IER/QSPI_IDR/QSPI_IMR  */
+#define QSPI_SR_RDRF                    BIT(0)
+#define QSPI_SR_TDRE                    BIT(1)
+#define QSPI_SR_TXEMPTY                 BIT(2)
+#define QSPI_SR_OVRES                   BIT(3)
+#define QSPI_SR_CSR                     BIT(8)
+#define QSPI_SR_CSS                     BIT(9)
+#define QSPI_SR_INSTRE                  BIT(10)
+#define QSPI_SR_QSPIENS                 BIT(24)
+
+#define QSPI_SR_CMD_COMPLETED	(QSPI_SR_INSTRE | QSPI_SR_CSR)
+
+/* Bitfields in QSPI_SCR (Serial Clock Register) */
+#define QSPI_SCR_CPOL                   BIT(0)
+#define QSPI_SCR_CPHA                   BIT(1)
+#define QSPI_SCR_SCBR_MASK              GENMASK(15, 8)
+#define QSPI_SCR_SCBR(n)                (((n) << 8) & QSPI_SCR_SCBR_MASK)
+#define QSPI_SCR_DLYBS_MASK             GENMASK(23, 16)
+#define QSPI_SCR_DLYBS(n)               (((n) << 16) & QSPI_SCR_DLYBS_MASK)
+
+/* Bitfields in QSPI_ICR (Instruction Code Register) */
+#define QSPI_ICR_INST_MASK              GENMASK(7, 0)
+#define QSPI_ICR_INST(inst)             (((inst) << 0) & QSPI_ICR_INST_MASK)
+#define QSPI_ICR_OPT_MASK               GENMASK(23, 16)
+#define QSPI_ICR_OPT(opt)               (((opt) << 16) & QSPI_ICR_OPT_MASK)
+
+/* Bitfields in QSPI_IFR (Instruction Frame Register) */
+#define QSPI_IFR_WIDTH_MASK             GENMASK(2, 0)
+#define QSPI_IFR_WIDTH_SINGLE_BIT_SPI   (0 << 0)
+#define QSPI_IFR_WIDTH_DUAL_OUTPUT      (1 << 0)
+#define QSPI_IFR_WIDTH_QUAD_OUTPUT      (2 << 0)
+#define QSPI_IFR_WIDTH_DUAL_IO          (3 << 0)
+#define QSPI_IFR_WIDTH_QUAD_IO          (4 << 0)
+#define QSPI_IFR_WIDTH_DUAL_CMD         (5 << 0)
+#define QSPI_IFR_WIDTH_QUAD_CMD         (6 << 0)
+#define QSPI_IFR_INSTEN                 BIT(4)
+#define QSPI_IFR_ADDREN                 BIT(5)
+#define QSPI_IFR_OPTEN                  BIT(6)
+#define QSPI_IFR_DATAEN                 BIT(7)
+#define QSPI_IFR_OPTL_MASK              GENMASK(9, 8)
+#define QSPI_IFR_OPTL_1BIT              (0 << 8)
+#define QSPI_IFR_OPTL_2BIT              (1 << 8)
+#define QSPI_IFR_OPTL_4BIT              (2 << 8)
+#define QSPI_IFR_OPTL_8BIT              (3 << 8)
+#define QSPI_IFR_ADDRL                  BIT(10)
+#define QSPI_IFR_TFRTYP_MASK            GENMASK(13, 12)
+#define QSPI_IFR_TFRTYP_TRSFR_READ      (0 << 12)
+#define QSPI_IFR_TFRTYP_TRSFR_READ_MEM  (1 << 12)
+#define QSPI_IFR_TFRTYP_TRSFR_WRITE     (2 << 12)
+#define QSPI_IFR_TFRTYP_TRSFR_WRITE_MEM (3 << 13)
+#define QSPI_IFR_CRM                    BIT(14)
+#define QSPI_IFR_NBDUM_MASK             GENMASK(20, 16)
+#define QSPI_IFR_NBDUM(n)               (((n) << 16) & QSPI_IFR_NBDUM_MASK)
+
+/* Bitfields in QSPI_SMR (Scrambling Mode Register) */
+#define QSPI_SMR_SCREN                  BIT(0)
+#define QSPI_SMR_RVDIS                  BIT(1)
+
+/* Bitfields in QSPI_WPMR (Write Protection Mode Register) */
+#define QSPI_WPMR_WPEN                  BIT(0)
+#define QSPI_WPMR_WPKEY_MASK            GENMASK(31, 8)
+#define QSPI_WPMR_WPKEY(wpkey)          (((wpkey) << 8) & QSPI_WPMR_WPKEY_MASK)
+
+/* Bitfields in QSPI_WPSR (Write Protection Status Register) */
+#define QSPI_WPSR_WPVS                  BIT(0)
+#define QSPI_WPSR_WPVSRC_MASK           GENMASK(15, 8)
+#define QSPI_WPSR_WPVSRC(src)           (((src) << 8) & QSPI_WPSR_WPVSRC)
+
+
+struct atmel_qspi {
+	void __iomem		*regs;
+	void __iomem		*mem;
+	struct clk		*clk;
+	struct platform_device	*pdev;
+	u32			pending;
+
+	struct spi_nor		nor;
+	u32			clk_rate;
+	struct completion	cmd_completion;
+};
+
+struct atmel_qspi_command {
+	union {
+		struct {
+			u32	instruction:1;
+			u32	address:3;
+			u32	mode:1;
+			u32	dummy:1;
+			u32	data:1;
+			u32	reserved:25;
+		}		bits;
+		u32	word;
+	}	enable;
+	u8	instruction;
+	u8	mode;
+	u8	num_mode_cycles;
+	u8	num_dummy_cycles;
+	u32	address;
+
+	size_t		buf_len;
+	const void	*tx_buf;
+	void		*rx_buf;
+};
+
+/* Register access functions */
+static inline u32 qspi_readl(struct atmel_qspi *aq, u32 reg)
+{
+	return readl_relaxed(aq->regs + reg);
+}
+
+static inline void qspi_writel(struct atmel_qspi *aq, u32 reg, u32 value)
+{
+	writel_relaxed(value, aq->regs + reg);
+}
+
+static int atmel_qspi_run_transfer(struct atmel_qspi *aq,
+				   const struct atmel_qspi_command *cmd)
+{
+	void __iomem *ahb_mem;
+
+	/* Then fallback to a PIO transfer (memcpy() DOES NOT work!) */
+	ahb_mem = aq->mem;
+	if (cmd->enable.bits.address)
+		ahb_mem += cmd->address;
+	if (cmd->tx_buf)
+		_memcpy_toio(ahb_mem, cmd->tx_buf, cmd->buf_len);
+	else
+		_memcpy_fromio(cmd->rx_buf, ahb_mem, cmd->buf_len);
+
+	return 0;
+}
+
+#ifdef DEBUG
+static void atmel_qspi_debug_command(struct atmel_qspi *aq,
+				     const struct atmel_qspi_command *cmd,
+				     u32 ifr)
+{
+	u8 cmd_buf[SPI_NOR_MAX_CMD_SIZE];
+	size_t len = 0;
+	int i;
+
+	if (cmd->enable.bits.instruction)
+		cmd_buf[len++] = cmd->instruction;
+
+	for (i = cmd->enable.bits.address-1; i >= 0; --i)
+		cmd_buf[len++] = (cmd->address >> (i << 3)) & 0xff;
+
+	if (cmd->enable.bits.mode)
+		cmd_buf[len++] = cmd->mode;
+
+	if (cmd->enable.bits.dummy) {
+		int num = cmd->num_dummy_cycles;
+
+		switch (ifr & QSPI_IFR_WIDTH_MASK) {
+		case QSPI_IFR_WIDTH_SINGLE_BIT_SPI:
+		case QSPI_IFR_WIDTH_DUAL_OUTPUT:
+		case QSPI_IFR_WIDTH_QUAD_OUTPUT:
+			num >>= 3;
+			break;
+		case QSPI_IFR_WIDTH_DUAL_IO:
+		case QSPI_IFR_WIDTH_DUAL_CMD:
+			num >>= 2;
+			break;
+		case QSPI_IFR_WIDTH_QUAD_IO:
+		case QSPI_IFR_WIDTH_QUAD_CMD:
+			num >>= 1;
+			break;
+		default:
+			return;
+		}
+
+		for (i = 0; i < num; ++i)
+			cmd_buf[len++] = 0;
+	}
+
+	/* Dump the SPI command */
+	print_hex_dump(KERN_DEBUG, "qspi cmd: ", DUMP_PREFIX_NONE,
+		       32, 1, cmd_buf, len, false);
+
+#ifdef VERBOSE_DEBUG
+	/* If verbose debug is enabled, also dump the TX data */
+	if (cmd->enable.bits.data && cmd->tx_buf)
+		print_hex_dump(KERN_DEBUG, "qspi tx : ", DUMP_PREFIX_NONE,
+			       32, 1, cmd->tx_buf, cmd->buf_len, false);
+#endif
+}
+#else
+#define atmel_qspi_debug_command(aq, cmd, ifr)
+#endif
+
+static int atmel_qspi_run_command(struct atmel_qspi *aq,
+				  const struct atmel_qspi_command *cmd,
+				  u32 ifr_tfrtyp, u32 ifr_width)
+{
+	u32 iar, icr, ifr, sr;
+	int err = 0;
+
+	iar = 0;
+	icr = 0;
+	ifr = ifr_tfrtyp | ifr_width;
+
+	/* Compute instruction parameters */
+	if (cmd->enable.bits.instruction) {
+		icr |= QSPI_ICR_INST(cmd->instruction);
+		ifr |= QSPI_IFR_INSTEN;
+	}
+
+	/* Compute address parameters */
+	switch (cmd->enable.bits.address) {
+	case 4:
+		ifr |= QSPI_IFR_ADDRL;
+		/* fall through to the 24bit (3 byte) address case. */
+	case 3:
+		iar = (cmd->enable.bits.data) ? 0 : cmd->address;
+		ifr |= QSPI_IFR_ADDREN;
+		break;
+	case 0:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Compute option parameters */
+	if (cmd->enable.bits.mode && cmd->num_mode_cycles) {
+		u32 mode_cycle_bits, mode_bits;
+
+		icr |= QSPI_ICR_OPT(cmd->mode);
+		ifr |= QSPI_IFR_OPTEN;
+
+		switch (ifr & QSPI_IFR_WIDTH_MASK) {
+		case QSPI_IFR_WIDTH_SINGLE_BIT_SPI:
+		case QSPI_IFR_WIDTH_DUAL_OUTPUT:
+		case QSPI_IFR_WIDTH_QUAD_OUTPUT:
+			mode_cycle_bits = 1;
+			break;
+		case QSPI_IFR_WIDTH_DUAL_IO:
+		case QSPI_IFR_WIDTH_DUAL_CMD:
+			mode_cycle_bits = 2;
+			break;
+		case QSPI_IFR_WIDTH_QUAD_IO:
+		case QSPI_IFR_WIDTH_QUAD_CMD:
+			mode_cycle_bits = 4;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		mode_bits = cmd->num_mode_cycles * mode_cycle_bits;
+		switch (mode_bits) {
+		case 1:
+			ifr |= QSPI_IFR_OPTL_1BIT;
+			break;
+
+		case 2:
+			ifr |= QSPI_IFR_OPTL_2BIT;
+			break;
+
+		case 4:
+			ifr |= QSPI_IFR_OPTL_4BIT;
+			break;
+
+		case 8:
+			ifr |= QSPI_IFR_OPTL_8BIT;
+			break;
+
+		default:
+			return -EINVAL;
+		}
+	}
+
+	/* Set number of dummy cycles */
+	if (cmd->enable.bits.dummy)
+		ifr |= QSPI_IFR_NBDUM(cmd->num_dummy_cycles);
+
+	/* Set data enable */
+	if (cmd->enable.bits.data) {
+		ifr |= QSPI_IFR_DATAEN;
+
+		/* Special case for Continuous Read Mode */
+		if (!cmd->tx_buf && !cmd->rx_buf)
+			ifr |= QSPI_IFR_CRM;
+	}
+
+	/* Clear pending interrupts */
+	(void)qspi_readl(aq, QSPI_SR);
+
+	/* Set QSPI Instruction Frame registers */
+	atmel_qspi_debug_command(aq, cmd, ifr);
+	qspi_writel(aq, QSPI_IAR, iar);
+	qspi_writel(aq, QSPI_ICR, icr);
+	qspi_writel(aq, QSPI_IFR, ifr);
+
+	/* Skip to the final steps if there is no data */
+	if (!cmd->enable.bits.data)
+		goto no_data;
+
+	/* Dummy read of QSPI_IFR to synchronize APB and AHB accesses */
+	(void)qspi_readl(aq, QSPI_IFR);
+
+	/* Stop here for continuous read */
+	if (!cmd->tx_buf && !cmd->rx_buf)
+		return 0;
+	/* Send/Receive data */
+	err = atmel_qspi_run_transfer(aq, cmd);
+
+	/* Release the chip-select */
+	qspi_writel(aq, QSPI_CR, QSPI_CR_LASTXFER);
+
+	if (err)
+		return err;
+
+#if defined(DEBUG) && defined(VERBOSE_DEBUG)
+	/*
+	 * If verbose debug is enabled, also dump the RX data in addition to
+	 * the SPI command previously dumped by atmel_qspi_debug_command()
+	 */
+	if (cmd->rx_buf)
+		print_hex_dump(KERN_DEBUG, "qspi rx : ", DUMP_PREFIX_NONE,
+			       32, 1, cmd->rx_buf, cmd->buf_len, false);
+#endif
+no_data:
+	/* Poll INSTRuction End status */
+	sr = qspi_readl(aq, QSPI_SR);
+	if ((sr & QSPI_SR_CMD_COMPLETED) == QSPI_SR_CMD_COMPLETED)
+		return err;
+
+	/* Wait for INSTRuction End interrupt */
+	reinit_completion(&aq->cmd_completion);
+	aq->pending = sr & QSPI_SR_CMD_COMPLETED;
+	qspi_writel(aq, QSPI_IER, QSPI_SR_CMD_COMPLETED);
+	if (!wait_for_completion_timeout(&aq->cmd_completion,
+					 msecs_to_jiffies(1000)))
+		err = -ETIMEDOUT;
+	qspi_writel(aq, QSPI_IDR, QSPI_SR_CMD_COMPLETED);
+
+	return err;
+}
+
+static int atmel_qspi_read_reg(struct spi_nor *nor, u8 opcode,
+			       u8 *buf, int len)
+{
+	struct atmel_qspi *aq = nor->priv;
+	struct atmel_qspi_command cmd;
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.enable.bits.instruction = 1;
+	cmd.enable.bits.data = 1;
+	cmd.instruction = opcode;
+	cmd.rx_buf = buf;
+	cmd.buf_len = len;
+	return atmel_qspi_run_command(aq, &cmd, QSPI_IFR_TFRTYP_TRSFR_READ,
+				      QSPI_IFR_WIDTH_SINGLE_BIT_SPI);
+}
+
+static int atmel_qspi_write_reg(struct spi_nor *nor, u8 opcode,
+				u8 *buf, int len)
+{
+	struct atmel_qspi *aq = nor->priv;
+	struct atmel_qspi_command cmd;
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.enable.bits.instruction = 1;
+	cmd.enable.bits.data = (buf != NULL && len > 0);
+	cmd.instruction = opcode;
+	cmd.tx_buf = buf;
+	cmd.buf_len = len;
+	return atmel_qspi_run_command(aq, &cmd, QSPI_IFR_TFRTYP_TRSFR_WRITE,
+				      QSPI_IFR_WIDTH_SINGLE_BIT_SPI);
+}
+
+static ssize_t atmel_qspi_write(struct spi_nor *nor, loff_t to, size_t len,
+				const u_char *write_buf)
+{
+	struct atmel_qspi *aq = nor->priv;
+	struct atmel_qspi_command cmd;
+	ssize_t ret;
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.enable.bits.instruction = 1;
+	cmd.enable.bits.address = nor->addr_width;
+	cmd.enable.bits.data = 1;
+	cmd.instruction = nor->program_opcode;
+	cmd.address = (u32)to;
+	cmd.tx_buf = write_buf;
+	cmd.buf_len = len;
+	ret = atmel_qspi_run_command(aq, &cmd, QSPI_IFR_TFRTYP_TRSFR_WRITE_MEM,
+				     QSPI_IFR_WIDTH_SINGLE_BIT_SPI);
+	return (ret < 0) ? ret : len;
+}
+
+static int atmel_qspi_erase(struct spi_nor *nor, loff_t offs)
+{
+	struct atmel_qspi *aq = nor->priv;
+	struct atmel_qspi_command cmd;
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.enable.bits.instruction = 1;
+	cmd.enable.bits.address = nor->addr_width;
+	cmd.instruction = nor->erase_opcode;
+	cmd.address = (u32)offs;
+	return atmel_qspi_run_command(aq, &cmd, QSPI_IFR_TFRTYP_TRSFR_WRITE,
+				      QSPI_IFR_WIDTH_SINGLE_BIT_SPI);
+}
+
+static ssize_t atmel_qspi_read(struct spi_nor *nor, loff_t from, size_t len,
+			       u_char *read_buf)
+{
+	struct atmel_qspi *aq = nor->priv;
+	struct atmel_qspi_command cmd;
+	u8 num_mode_cycles, num_dummy_cycles;
+	u32 ifr_width;
+	ssize_t ret;
+
+	switch (nor->flash_read) {
+	case SPI_NOR_NORMAL:
+	case SPI_NOR_FAST:
+		ifr_width = QSPI_IFR_WIDTH_SINGLE_BIT_SPI;
+		break;
+
+	case SPI_NOR_DUAL:
+		ifr_width = QSPI_IFR_WIDTH_DUAL_OUTPUT;
+		break;
+
+	case SPI_NOR_QUAD:
+		ifr_width = QSPI_IFR_WIDTH_QUAD_OUTPUT;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	if (nor->read_dummy >= 2) {
+		num_mode_cycles = 2;
+		num_dummy_cycles = nor->read_dummy - 2;
+	} else {
+		num_mode_cycles = nor->read_dummy;
+		num_dummy_cycles = 0;
+	}
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.enable.bits.instruction = 1;
+	cmd.enable.bits.address = nor->addr_width;
+	cmd.enable.bits.mode = (num_mode_cycles > 0);
+	cmd.enable.bits.dummy = (num_dummy_cycles > 0);
+	cmd.enable.bits.data = 1;
+	cmd.instruction = nor->read_opcode;
+	cmd.address = (u32)from;
+	cmd.mode = 0xff; /* This value prevents from entering the 0-4-4 mode */
+	cmd.num_mode_cycles = num_mode_cycles;
+	cmd.num_dummy_cycles = num_dummy_cycles;
+	cmd.rx_buf = read_buf;
+	cmd.buf_len = len;
+	ret = atmel_qspi_run_command(aq, &cmd, QSPI_IFR_TFRTYP_TRSFR_READ_MEM,
+				     ifr_width);
+	return (ret < 0) ? ret : len;
+}
+
+static int atmel_qspi_init(struct atmel_qspi *aq)
+{
+	unsigned long src_rate;
+	u32 mr, scr, scbr;
+
+	/* Reset the QSPI controller */
+	qspi_writel(aq, QSPI_CR, QSPI_CR_SWRST);
+
+	/* Set the QSPI controller in Serial Memory Mode */
+	mr = QSPI_MR_NBBITS(8) | QSPI_MR_SSM;
+	qspi_writel(aq, QSPI_MR, mr);
+
+	src_rate = clk_get_rate(aq->clk);
+	if (!src_rate)
+		return -EINVAL;
+
+	/* Compute the QSPI baudrate */
+	scbr = DIV_ROUND_UP(src_rate, aq->clk_rate);
+	if (scbr > 0)
+		scbr--;
+	scr = QSPI_SCR_SCBR(scbr);
+	qspi_writel(aq, QSPI_SCR, scr);
+
+	/* Enable the QSPI controller */
+	qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIEN);
+
+	return 0;
+}
+
+static irqreturn_t atmel_qspi_interrupt(int irq, void *dev_id)
+{
+	struct atmel_qspi *aq = (struct atmel_qspi *)dev_id;
+	u32 status, mask, pending;
+
+	status = qspi_readl(aq, QSPI_SR);
+	mask = qspi_readl(aq, QSPI_IMR);
+	pending = status & mask;
+
+	if (!pending)
+		return IRQ_NONE;
+
+	aq->pending |= pending;
+	if ((aq->pending & QSPI_SR_CMD_COMPLETED) == QSPI_SR_CMD_COMPLETED)
+		complete(&aq->cmd_completion);
+
+	return IRQ_HANDLED;
+}
+
+static int atmel_qspi_probe(struct platform_device *pdev)
+{
+	struct device_node *child, *np = pdev->dev.of_node;
+	struct atmel_qspi *aq;
+	struct resource *res;
+	struct spi_nor *nor;
+	struct mtd_info *mtd;
+	int irq, err = 0;
+
+	if (of_get_child_count(np) != 1)
+		return -ENODEV;
+	child = of_get_next_child(np, NULL);
+
+	aq = devm_kzalloc(&pdev->dev, sizeof(*aq), GFP_KERNEL);
+	if (!aq) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	platform_set_drvdata(pdev, aq);
+	init_completion(&aq->cmd_completion);
+	aq->pdev = pdev;
+
+	/* Map the registers */
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi_base");
+	aq->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(aq->regs)) {
+		dev_err(&pdev->dev, "missing registers\n");
+		err = PTR_ERR(aq->regs);
+		goto exit;
+	}
+
+	/* Map the AHB memory */
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi_mmap");
+	aq->mem = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(aq->mem)) {
+		dev_err(&pdev->dev, "missing AHB memory\n");
+		err = PTR_ERR(aq->mem);
+		goto exit;
+	}
+
+	/* Get the peripheral clock */
+	aq->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(aq->clk)) {
+		dev_err(&pdev->dev, "missing peripheral clock\n");
+		err = PTR_ERR(aq->clk);
+		goto exit;
+	}
+
+	/* Enable the peripheral clock */
+	err = clk_prepare_enable(aq->clk);
+	if (err) {
+		dev_err(&pdev->dev, "failed to enable the peripheral clock\n");
+		goto exit;
+	}
+
+	/* Request the IRQ */
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "missing IRQ\n");
+		err = irq;
+		goto disable_clk;
+	}
+	err = devm_request_irq(&pdev->dev, irq, atmel_qspi_interrupt,
+			       0, dev_name(&pdev->dev), aq);
+	if (err)
+		goto disable_clk;
+
+	/* Setup the spi-nor */
+	nor = &aq->nor;
+	mtd = &nor->mtd;
+
+	nor->dev = &pdev->dev;
+	spi_nor_set_flash_node(nor, child);
+	nor->priv = aq;
+	mtd->priv = nor;
+
+	nor->read_reg = atmel_qspi_read_reg;
+	nor->write_reg = atmel_qspi_write_reg;
+	nor->read = atmel_qspi_read;
+	nor->write = atmel_qspi_write;
+	nor->erase = atmel_qspi_erase;
+
+	err = of_property_read_u32(child, "spi-max-frequency", &aq->clk_rate);
+	if (err < 0)
+		goto disable_clk;
+
+	err = atmel_qspi_init(aq);
+	if (err)
+		goto disable_clk;
+
+	err = spi_nor_scan(nor, NULL, SPI_NOR_QUAD);
+	if (err)
+		goto disable_clk;
+
+	err = mtd_device_register(mtd, NULL, 0);
+	if (err)
+		goto disable_clk;
+
+	of_node_put(child);
+
+	return 0;
+
+disable_clk:
+	clk_disable_unprepare(aq->clk);
+exit:
+	of_node_put(child);
+
+	return err;
+}
+
+static int atmel_qspi_remove(struct platform_device *pdev)
+{
+	struct atmel_qspi *aq = platform_get_drvdata(pdev);
+
+	mtd_device_unregister(&aq->nor.mtd);
+	qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIDIS);
+	clk_disable_unprepare(aq->clk);
+	return 0;
+}
+
+
+static const struct of_device_id atmel_qspi_dt_ids[] = {
+	{ .compatible = "atmel,sama5d2-qspi" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, atmel_qspi_dt_ids);
+
+static struct platform_driver atmel_qspi_driver = {
+	.driver = {
+		.name	= "atmel_qspi",
+		.of_match_table	= atmel_qspi_dt_ids,
+	},
+	.probe		= atmel_qspi_probe,
+	.remove		= atmel_qspi_remove,
+};
+module_platform_driver(atmel_qspi_driver);
+
+MODULE_AUTHOR("Cyrille Pitchen <[e-mail]>");
+MODULE_DESCRIPTION("Atmel QSPI Controller driver");
+MODULE_LICENSE("GPL v2");